Field of the Disclosure
The present disclosure relates to a display apparatus for displaying monitor video.
Description of the Related Art
With the increase in the use of monitoring cameras in recent years, the need for efficiently monitoring video images of many monitoring cameras is also increasing. To monitor the video of many monitoring cameras, it is common to simultaneously display a plurality of video images of monitoring cameras, for example, by dividing the monitor area of one monitor into a plurality of areas or arranging a plurality of monitors. However, when there are many monitoring cameras, video images of all the cameras cannot be simultaneously displayed on the monitor, therefore it is necessary to display video images on the monitor by switching them.
As a method for switching video images displayed on the monitor, it is common to collectively switch video display thereon at intervals of a fixed display time. However, the video images of a plurality of monitoring cameras include both of video images which require time for a monitoring person to grasp contents and video images which do not require monitoring time. For example, in a case where motions of persons and objects are carefully monitored, the video image showing many captured images of persons and objects requires much time to grasp contents in accordance with the number of persons and objects.
When the person size is small in the video image, many shielding objects are present, or the brightness is low, more careful monitoring is required, which causes the monitoring person to take much time to grasp video contents. On the other hand, video which is not picking an image of person does not require much time to grasp the contents. In this case, in a general display switching method, the video which requires time for a monitoring person to grasp the contents and the video which does not require time to grasp the contents may be displayed in the same time, and video display is switched before the monitoring person completely grasps the contents of each video image.
U.S. Pat. No. 3,763,981 and U.S. Pat. No. 4,905,761 discuss techniques related to a method for switching display of a plurality of video images. U.S. Pat. No. 3,763,981 discusses a method for prolonging the display time according to the degree of a temporal change of each video image in a display apparatus which is configured to display a plurality of monitor video images one after another within one area.
U.S. Pat. No. 4,905,761 is related to a system for displaying still images on a frame basis indicating temporal changes of a video image captured by one monitoring camera in a plurality of divided areas on one monitor. U.S. Pat. No. 4,905,761 discusses a technique for determining whether the change of the video is occurring in any frame image when switching the display target frame and, if the change is occurring, continues display of frames captured before the change to enable comparison between frames captured before and after the change.
The technique discussed in U.S. Pat. No. 3,763,981 prolongs the display time of a video image showing a major change, and therefore as its effect the monitoring person does not easily overlook the change in the video. However, this technique displays one video image in one area. Therefore, when there are many monitoring cameras, this technique is unable to simultaneously monitor video images of a plurality of monitoring cameras. The technique discussed in U.S. Pat. No. 4,905,761 simultaneously displays video images before and after the change has occurred, therefore as its effect the monitoring person can easily grasp changes in the video image. However, this technique can handle video images of only one monitoring camera and therefore is not capable of simultaneously monitoring video images of many monitoring cameras.
The techniques in U.S. Pat. No. 3,763,981 and U.S. Pat. No. 4,905,761 do not switch video images of a plurality of monitoring cameras to display them and therefore are not capable of supporting a situation where many monitoring cameras are operating. Although the techniques in U.S. Pat. No. 3,763,981 and U.S. Pat. No. 4,905,761 perform control by switching display according to the change amount of a video image, these techniques cannot take into consideration various factors which have an influence when grasping video contents such as the number of persons and objects and person size. Therefore, these techniques cannot control video display according to the visibility of video images.